The invention relates to a color television receiver having a converter circuit for converting a time division multiplex television signal into simultaneous signals, said time division multiplex signal having an interrupted sequence of a first information component relating to luminance information occurring in first periods, the first information components being separated by a further sequence of a second and a third information component relating to chrominance information occurring in second and third periods, respectively, said simultaneous signals corresponding to the first, second and third information components and repeated third and second information components, respectively, said second and third information components, either repeated or not, being expanded in time so that they occur in the simultaneous signals during the same first period or a fourth period, respectively, as the first information components when said periods correspond to television line scan periods, the converter circuit including signal sampling, expansion and repetition circuit disposed between a circuit input and a circuit output for the second and third information components relating to chrominance information, said circuits being formed with shift registers having different write and read rates under the control of clock pulses of different clock pulse frequencies. The invention also relates to an integrated circuit suitable therefor.
A color television receiver of this kind can be used with, for example, a color television system as described in a public report "Experimental and Development Report 118/82" by the English "Independent Broadcasting Authority" (I.B.A.) entitled "MAC: A Television System for High-Quality Satellite Broadcasting". The report gives several variants for a so-called MAC (Multiplexed Analog Component) picture coding. As is apparent from a survey table on page 9 of the report, it holds for all variants that the luminance and chrominance information each undergo a time compression, with the compression for the chrominance information being twice that of the luminance information. The chrominance information comprising two components per line period and alternately one of the two occurs compressed in time in the time division multplex coded signal. The luminance information associated with each line period is present in a time-compressed state in this signal. For the time compression associated with the luminance information the report gives the factors 2/3 and 3/4, leading to time compression factors of 1/3 and 3/8 for the chrominance information. The picture information per line period in the time division multiplex coded signal is sequentially composed of the time-compressed luminance information and one of the two associated time-compressed chrominance information components.
In the receiver the time division multiplex coded signal is derived from the signal received through the transmission channel, i.e. the satellite connection, which signal is applied to the circuit described which supplies a time expansion for the luminance and chrominance information with the aid of synchronizing and identification information and which repeatedly supplies the expanded chrominance information over the subsequent line period.
For the variants described a system may be considered in which the luminance information is not compressed or is hardly compressed so that only the chrominance information components require signal expansion.
Repetition of the chrominance information may be realized in the receiver in known manner by using a delay device having a delay time of one line period. This delay device succeeds the expansion circuit which supplies the chrominance information directly during one line period and through the delay device during the subsequent line period. In this case the requirements apply that the delay device delays the signal only over exactly one line period and does not exert any further influence on amplitudes, frequencies and phases. Compliance with these requirements leads to the use of an expensive, accurate delay device in which ageing phenomena should not exert any influence.